That ratio is a good jumping off point for other manual methods, but when I say "jumping off," I mean it! For example in total immersion methods like the French press, you have a lot more leeway to play with brew strength because extraction rate is tied only to the grind and the dwell time. So you can updose or underdose as much as you like.

In gravity methods like the Chemex, every time you change the dose, you affect the extraction rate. Getting the two in harmony is the real trick to making great coffee, and the numbers Stephen tosses out here are tried and true.